F.B.I. Agents' Role Is Transformed by Terror Fight

... Spending two days with Agent Bernardino’s 21-member threat squad, known as Counterterrorism 6, or CT-6, offered a rare window on the daily workings of an F.B.I. transformed after the attacks of Sept. 11, 2001. The bureau now ranks fighting terrorism as its No. 1 priority. It has doubled the number of agents assigned to counterterrorism duties to roughly 5,000 people, and has created new squads across the country that focus more on deterring and disrupting terrorism than on solving crimes...

...Federal agents say a major lesson of the Sept. 11 attacks is that all credible reports of possible terrorist activity must be checked. And they say it is more efficient for one squad with specially trained investigators to assess these tips, allowing other agents to stay focused on longer-term terrorist inquiries.

The squad’s work here has yielded important results, officials say. In March 2008, Seyed Maghloubi, an Iranian-born American citizen, was sentenced to 41 months in prison for plotting to illegally export 100,000 Uzi submachine guns to Iran, via Dubai.

His arrest stemmed from a tip from a police informant whom Mr. Maghloubi contacted about buying the weapons. The threat squad picked up the tip and developed information that led to a federal sting operation against Mr. Maghloubi.

Responsible for overseeing seven counties and 19 million people in Southern California, the threat squad was created in May 2004 after threats to shopping malls on the West Side of Los Angeles diverted about 100 agents from other counterterrorism inquiries...